Alkaline Electrolytes for Pseudocapacitors

FIGURE 2.11 (a) Charge per target carbon atom (circled) in undoped and nitrogen-doped 

Similarly, using C03O4 as pseudocapacitive materials in the KOH electrolyte, the surface faradaic reaction is involved with OH- ions adsorption/desorption or inser-tion/extraction accompanied by the charge transfer process. This can be expressed as follows [127,128]  

It is interesting to note that Feng et al. [126] prepared sub-3 nm C03O4 nanofilms (Fignre 2.12), and a very high specific capacitance of 1400 F g- was reported in 2 M 

FIGURE 2.13 Cyclic voltammograms of VN film with a thickness of480 nm at 200 mV s with different concentrations of KOH after 100 cycles. In addition, the cyclic voltammo-gram of 1 M NEt4Bp4 in ACN at 200 mV s versns Ag/AgCl, is also shown. (Reprinted from Electrochimica Acta, 141, Lucio-Porto, R. et al., VN thin films as electrode materials for electrochemical capacitors, 203-211, Copyright 2014, with permission from Elsevier.) 

Furthermore, for pseudocapacitive materials, the cycle stability is a major concern. Besides the repeated ion intercalation/deintercalation-related failure mechanism, it was also found that the decrease of the capacitive performance after long-term charging/discharging cycling might also be related to the dissolution of electrode materials in alkaline electrolytes [142]. Joseph et al. [142] found the cycling stability of Ni3(N03)2(0H)4 in LiOH was higher than that in KOH and NaOH electrolytes. Inductively coupled plasma atomic emission spectroscopy (ICP-AES) analysis showed the evidence of the Ni dissolution into the electrolyte and found the dissolution of 

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